U.S. patent application number 17/609936 was filed with the patent office on 2022-08-04 for formulation for a fibrous non-woven facing material.
The applicant listed for this patent is Owens Corning Intellectual Capital, LLC. Invention is credited to Paul Geel, Hitesh Khandel, Domenico Lacamera, Joshua Ritterbex.
Application Number | 20220243400 17/609936 |
Document ID | / |
Family ID | 1000006334482 |
Filed Date | 2022-08-04 |
United States Patent
Application |
20220243400 |
Kind Code |
A1 |
Khandel; Hitesh ; et
al. |
August 4, 2022 |
FORMULATION FOR A FIBROUS NON-WOVEN FACING MATERIAL
Abstract
The present invention provides a formulation for a fibrous
non-woven facing material, wherein the formulation comprises a
binder, a filler, and an extender. The extender has an median
particle size, d.sub.50, which is equal to or less than 3.5 .mu.m,
and a non-spherical morphology. The filler has an median particle
size, d.sub.50, which is equal to or less than 3.0 .mu.m and
wherein the filler has a d.sub.10 equal to or less than 1.0 .mu.m
and a d.sub.90 equal to or less than 6.0 .mu.m. The formulation
comprises less than 13 wt % titanium dioxide on a dry solids basis.
Also provided is a fibrous non-woven facing material comprising the
formulation, a process for preparing the fibrous non-woven facing
material and a fibrous non-woven facing material obtained by said
process.
Inventors: |
Khandel; Hitesh; (Zwolle,
NL) ; Lacamera; Domenico; (Amsterdam, NL) ;
Geel; Paul; (Heaveadorp, NL) ; Ritterbex; Joshua;
(Renkum, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Owens Corning Intellectual Capital, LLC |
Toledo |
OH |
US |
|
|
Family ID: |
1000006334482 |
Appl. No.: |
17/609936 |
Filed: |
May 7, 2020 |
PCT Filed: |
May 7, 2020 |
PCT NO: |
PCT/US20/31740 |
371 Date: |
November 9, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D06M 11/76 20130101;
D21H 17/68 20130101; D21H 27/20 20130101; D04H 1/587 20130101; D21H
17/675 20130101; D21H 21/28 20130101; D21H 17/74 20130101; D21H
17/20 20130101; D21H 13/40 20130101 |
International
Class: |
D21H 17/00 20060101
D21H017/00; D21H 17/67 20060101 D21H017/67; D21H 17/68 20060101
D21H017/68; D21H 17/20 20060101 D21H017/20; D21H 13/40 20060101
D21H013/40; D21H 21/28 20060101 D21H021/28; D21H 27/20 20060101
D21H027/20; D04H 1/587 20060101 D04H001/587; D06M 11/76 20060101
D06M011/76 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2019 |
EP |
19173931.7 |
Claims
1. A formulation for a fibrous non-woven facing material, wherein
the formulation comprises: (i) a binder; (ii) a filler; and (iii)
an extender; wherein a median particle size, d.sub.50, of the
extender is equal to or less than 3.5 .mu.m, and wherein the
extender has a non-spherical morphology; wherein a median particle
size, d.sub.50, of the filler is equal to or less than 3.0 .mu.m
and wherein the filler has a d.sub.10 equal to or less than 1.0
.mu.m and a d.sub.90 equal to or less than 6.0 .mu.m; and wherein
the formulation comprises less than 13 wt % titanium dioxide on a
dry solids basis.
2. The formulation according to claim 1, wherein the extender has a
non-spherical morphology consisting essentially of plate-shaped
particles, rod-shaped particles, cubic or cuboid-shaped particles,
pseudo-cubic shaped particles or cigar-shaped particles.
3. The formulation according to claim 1, wherein the extender
comprises kaolin, calcium carbonate, Huntite, magnesium carbonate,
calcium-magnesium carbonate, or a mixture thereof.
4. The formulation according to claim 1, wherein the filler
comprises calcium carbonate or aluminium trihydrate.
5. The formulation according to claim 1, wherein the filler has a
refractive index of less than 2.5.
6. The formulation according to claim 1, wherein the extender has a
refractive index of less than 2.5.
7. The formulation according to claim 1, wherein the formulation
does not include a pigment having a refractive index of 2.5 or
more.
8. The formulation according to claim 1, wherein the median
particle size, d.sub.50, of the extender is equal to or less than
3.5 .mu.m and greater than 0.6 .mu.m.
9. The formulation according to claim 1, wherein the average
particle size, d.sub.90, of the extender is between 4 and 20
.mu.m.
10. The formulation according to claim 1, wherein the median
particle size, d.sub.50, of the filler is equal to or less than 0.8
.mu.m.
11. The formulation according to claim 1, wherein the filler has a
d.sub.50 equal to or less than 1.5 .mu.m, a d.sub.10 equal to or
less than 0.5 .mu.m and a d.sub.90 equal to or less than 5 .mu.m
and wherein the filler comprises calcium carbonate, kaolin,
magnesium carbonate, or a mixture thereof.
12. The formulation according to claim 1, wherein the filler has a
d.sub.50 equal to or less than 2.5 .mu.m, a d.sub.10 equal to or
less than 0.9 .mu.m and a d.sub.90 equal to or less than 6.0 .mu.m,
and wherein the filler comprises aluminium trihydrate.
13. The formulation according to claim 1, wherein the formulation
comprises less than 10 wt % of titanium dioxide, on a dry solids
basis.
14. The formulation according to claim 1, wherein the formulation
is substantially free of titanium dioxide.
15. The formulation according to claim 1, wherein the binder
comprises from 5 wt % to 35 wt % of the dry solids of the
formulation.
16. The formulation according to claim 1, wherein the extender
comprises from 5 wt % to 90 wt % of the dry solids of the
formulation.
17. The formulation according to claim 1, wherein the filler
comprises from 5 wt % to 90 wt % of the dry solids of the
formulation.
18. The formulation according to claim 1, wherein a weight ratio
based on dry solids of the binder to the extender is from 0.05:1 to
7:1.
19. The formulation according to claim 1, wherein a weight ratio
based on dry solids of the binder to a sum of the extender and the
filler is from 0.05:1 to 7:2.
20. The formulation according to claim 1, wherein a weight ratio
based on dry solids of the extender to the filler is from 0.05:1 to
18:1.
21. The formulation according to claim 1, wherein the formulation
has a total solids content of from 30 to 85%.
22. A fibrous non-woven facing material comprising: a non-woven
base veil comprising a plurality of randomly oriented fibres; and a
formulation according to claim 1.
23. The fibrous non-woven facing material according to claim 22,
wherein the facing material is a non-woven wall-covering or ceiling
tile facer.
24. The fibrous non-woven facing material according to claim 22,
wherein the non-woven base veil has at least a first surface and a
second surface and the formulation at least partially coats the
first surface.
25. The fibrous non-woven facing material according to claim 22,
wherein the formulation at least partially impregnates the
non-woven base veil.
26. The fibrous non-woven facing material according to claim 22,
wherein the formulation substantially uniformly coats the first
surface of the non-woven base veil.
27. The fibrous non-woven facing material according to claim 22 in
the form of a roll.
28. A process for preparing a fibrous non-woven facing material
comprising: (a) providing a non-woven base veil comprising a
plurality of randomly oriented fibres; (b) applying a formulation
according to claim 1 to the non-woven base veil; and (c) heating to
form the fibrous non-woven facing material.
29. The process according to claim 28, wherein step (b) comprises
impregnating the base veil with the formulation.
30. The process according to claim 28, further comprising step (d)
of forming a roll of the fibrous non-woven facing material.
31. The process according to claim 28, wherein the fibrous
non-woven facing material is a non-woven wall covering or a ceiling
tile facer.
32. A fibrous non-woven facing material obtained by the process of
claim 28.
Description
FIELD
[0001] The present invention relates generally to a formulation for
a fibrous non-woven facing material, and more particularly, to a
formulation for a fibrous non-woven wall covering which does not
contain a substantial amount of titanium dioxide and yet maintains
opacity and whiteness levels and improves glue penetration. The
present invention also provides a fibrous non-woven facing material
comprising a non-woven base veil of randomly-oriented fibres and
the formulation defined herein, along with a process for preparing
the fibrous non-woven facing material.
BACKGROUND
[0002] Non-woven facing materials are used in numerous applications
and have particular application as pre-painted wall coverings.
Pre-painted wall coverings are products which are pasted onto walls
to provide good aesthetics and a smooth wall surface to which paint
can be applied. They typically include a non-woven base veil
composed of fibres and a formulation impregnated therein which
contains a binder, a titanium dioxide pigment, and filler.
[0003] Titanium dioxide is not, however, a desirable component for
formulations intended for use in non-woven wall coverings. Not only
does titanium dioxide have high cost volatility, but there are
rising health and environmental concerns around this compound.
There has, for example, been a growing awareness that TiO.sub.2 is
a significant contributor to the carbon footprint of such
formulations.
[0004] As is known in the art, TiO.sub.2 is used most widely as a
white pigment due to its brightness and very high refractive index.
Hence in order to completely replace TiO.sub.2, opacity and
whiteness of the formulation must not be compromised. Any
replacement material must also be compatible with the other
components of the formulation, and be stable when applied to
fibres, including glass fibres, and subjected to heat.
Consequently, a formulation for a fibrous non-woven facing material
that contains a low level or even no titanium dioxide has not yet
been realised.
[0005] An additional problem with current formulations for fibrous
non-woven facing materials is glue penetration. Glue penetration is
important because it can cause contamination of tools while a
non-woven wall covering is being applied. This causes delay and
inconvenience for the painter or the like applying the wall
covering. Consequently, it would also be desirable to improve the
glue penetration properties of existing formulations for fibrous
non-woven facing materials.
[0006] Overall there remains a need in the art for a formulation
for a fibrous non-woven facing material which does not contain a
significant amount of titanium dioxide, but has opacity levels and
whiteness comparable to existing titanium dioxide formulations.
There is an additional need for a formulation with comparable or
improved glue penetration.
SUMMARY
[0007] It is an object of the present invention to provide a
formulation for a fibrous non-woven facing material, wherein the
formulation comprises (i) a binder, (ii) a filler, and (iii) an
extender. The median particle size, d.sub.50, of the extender is
equal to or less than 3.5 microns (.mu.m) and the extender has a
non-spherical morphology. The median particle size, d.sub.50, of
the filler is equal to or less than 3.0 microns (.mu.m). The filler
is also defined by having a d.sub.90 value of equal to or less than
6.0 microns (.mu.m) and a d.sub.10 value of equal to or less than
1.0 micron (.mu.m). The formulation further comprises less than 13
wt % titanium dioxide on a dry solids basis.
[0008] By "median particle size, d.sub.50", is meant the diameter
at which 50% of a sample's mass is comprised of smaller particles.
It is also known in the art as the "mass median diameter" or the
"average particle diameter by mass". In the present invention, the
median particle size, d.sub.50, is measured by laser diffraction
spectroscopy using, e.g. the Beckman Coulter LS 13 320
spectrometer. As is known in the art, the Beckman Coulter LS 13 320
measures the size distribution of particles suspended in either a
liquid or in dry powder form by using the principles of light
scattering. In the present invention, the material to be measured
was prepared as a 10 wt % aqueous slurry for analysis. Before
analysis, the sample was shaken by hand for a few minutes, and a
few drops then analysed with LS 13 320 using a Standard Optical
Model in which the fluid "real" refractive index was set at 1.333,
the sample "real" refractive index set at 1.5 and the "imaginary"
sample refractive index set at 0.1. These values were in line with
the Operating Manual for the LS 13 320 spectrometer.
[0009] In view of the non-spherical morphology of the extender, the
median particle size is calculated on the basis of "equivalent
spherical diameter". According to IUPAC, the equivalent diameter of
a non-spherical particle is equal to a diameter of a spherical
particle that exhibits identical properties to that of the
investigated non-spherical particle. For particles in non-turbulent
motion as in the present invention, the equivalent diameter is
identical to the diameter encountered in Stokes' law.
[0010] The terms "d.sub.10" and "d.sub.90" are defined below.
[0011] In various embodiments of the present invention, the
non-spherical morphology of the extender consists essentially of
plate-shaped particles, rod-shaped particles, cubic particles,
cuboid-shaped particles, pseudo-cubic shaped particles,
cigar-shaped particles, or a mixture thereof. The extender may also
comprise kaolin, calcium carbonate, Huntite
(Mg.sub.3Ca(CO.sub.3).sub.4), magnesium carbonate,
calcium-magnesium carbonate or a mixture thereof. In preferred
embodiments, the extender is a precipitated calcium carbonate.
[0012] In accordance with further embodiments of the present
invention, the filler comprises calcium carbonate or aluminium
trihydrate. In preferred embodiments, the filler is a ground
calcium carbonate or aluminium trihydrate. The aluminium trihydrate
may be precipitated, ground or autoclaved.
[0013] In accordance with various embodiments of the present
invention, the refractive index of the filler is equal to or less
than 2.5. In a preferred embodiment, the refractive index of the
filler is less than 2.0. In some embodiments of the present
invention, the refractive index of the extender is equal to or less
than 2.5. In a preferred embodiment, the refractive index of the
extender is less than 2.0.
[0014] Refractive index is measured according to standard methods
known in the art. It is defined as n=c/v, where c is the speed of
light in a vacuum, and v is the phase velocity of light in the
medium. Standard refractive index measurements are taken at the
"yellow doublet" sodium D line, with a wavelength of 589
nanometres. The refractive index of a material may also be
available from a publically available source or database such as
https://refractiveindex.info. A skilled person will also be aware
of other suitable sources
[0015] In accordance with various embodiments of the present
invention, the formulation does not include a pigment with a
refractive index of 2.5 or more. In preferred embodiments, the
formulation does not include a pigment with a refractive index of
2.4 or more. In more preferred embodiments, the formulation does
not include a pigment with a refractive index of 2.3 or more.
[0016] In accordance with various embodiments of the present
invention, the median particle size, d.sub.50, of the extender is
equal to or less than 3.5 .mu.m and greater than 0.6 .mu.m. In
preferred embodiments, the median particle size, d.sub.50, of the
extender is equal to or less than 3.5 .mu.m and greater than 1.0
.mu.m. As noted above, the median particle size is determined by
laser diffraction spectroscopy and is based on the equivalent
spherical diameter of the extender particles.
[0017] In accordance with various embodiments of the present
invention, the average particle size, d.sub.90, of the extender is
between 4 and 19 .mu.m. As will be appreciated by the skilled
person, d.sub.90 is the diameter at which 90% of a sample's mass is
comprised of smaller particles. The d.sub.90 values in the present
invention are also determined by laser diffraction using a LS 13
320 spectrometer as described herein. In particular, the material
to be measured is prepared as a 10 wt % aqueous slurry and then
analysed with the above-described Standard Optical Model on the LS
13 320 spectrometer. In preferred embodiments, the average particle
size d.sub.90, of the extender is between 6 and 19 .mu.m.
[0018] In accordance with various embodiments of the present
invention, the median particle size, d.sub.50, of the filler is
equal to or less than 1.5 .mu.m. In preferred embodiments, the
median particle size, d.sub.50, of the filler is equal to or less
than 1.0 .mu.m. In particularly preferred embodiments, the median
particle size, d.sub.50, of the filler is equal to or less than 0.8
.mu.m.
[0019] Additionally in accordance with various embodiments of the
present invention, the filler has a d.sub.10 value equal to or less
than 0.5 .mu.m and a d.sub.90 value equal to or less than 5 .mu.m.
In preferred embodiments, the filler has a d.sub.10 value equal to
or less than 0.3 .mu.m and a d.sub.90 value equal to or less than 3
.mu.m. In particularly preferred embodiments, the filler has a
d.sub.10 value equal to or less than 0.2 .mu.m and a d.sub.90 value
equal to or less than 2 .mu.m.
[0020] In such embodiments, the filler may comprise calcium
carbonate, kaolin, magnesium carbonate or a mixture thereof.
Preferably the filler is a calcium carbonate material.
[0021] In accordance with various alternative embodiments of the
present invention, the median particle size, d.sub.50, of the
filler is equal to or less than 2.5 .mu.m. In preferred
embodiments, the median particle size, d.sub.50, of the filler is
equal to or less than 2.0 .mu.m. In particularly preferred
embodiments, the median particle size, d.sub.50, of the filler is
equal to or less than 1.9 .mu.m.
[0022] Additionally in accordance with various embodiments of the
present invention, the filler has a d.sub.10 value equal to or less
than 0.9 .mu.m and a d.sub.90 value equal to or less than 6.0
.mu.m. In preferred embodiments, the filler has a d.sub.10 value
equal to or less than 0.8 .mu.m and a d.sub.90 value equal to or
less than 6.0 .mu.m. In particularly preferred embodiments, the
filler has a d.sub.10 value equal to or less than 0.6 .mu.m and a
d.sub.90 value equal to or less than 6.0 .mu.m.
[0023] In such embodiments, the filler may comprise aluminium
trihydrate.
[0024] In accordance with various embodiments of the present
invention, the formulation comprises less than 10 wt % of titanium
dioxide, on a dry solids basis. In preferred embodiments, the
formulation comprises less than 5 wt % of titanium dioxide, on a
dry solids basis. In particularly preferred embodiments, the
formulation comprises less than 1 wt % of titanium dioxide, on a
dry solids basis.
[0025] In other embodiments of the present invention, the
formulation is substantially free of titanium dioxide. By the term
"substantially free" is meant less than 0.5 wt % of titanium
dioxide on a dry solids basis, preferably less than 0.1 wt % and
more preferably less than 0.05 wt %.
[0026] In various embodiments of the present invention, the binder
comprises from 5 wt % to 35 wt % of the dry solids in the
formulation. The extender may comprise from 5 wt % to 90 wt % of
the dry solids in the formulation, and/or the filler may comprise
from 5 wt % to 90 wt % of the dry solids in the formulation.
[0027] In accordance with various embodiments of the present
invention, a weight ratio based on dry solids of the binder to the
extender (binder:extender) is from 0.05:1 to 7:1. In some
embodiments, a weight ratio based on dry solids of the binder to
the sum of the extender and filler (binder:extender+filler) is from
0.05:1 to 7:2. In some embodiments, a weight ratio based on dry
solids of the extender to the filler (extender:filler) is from
0.05:1 to 18:1. Moreover, in various embodiments of the present
invention, the formulation has a total solids content of from 30%
to 85%.
[0028] It is another object of the present invention to provide a
fibrous non-woven facing material comprising a non-woven base veil
comprising a plurality of randomly oriented fibres, and the
formulation as defined herein. In some embodiments of the present
invention, the fibrous non-woven facing material is a fibrous
non-woven wall-covering or a ceiling facer.
[0029] The non-woven base veil may have at least a first surface
and a second surface, and the formulation as defined herein may at
least partially coat said first surface. In some embodiments of the
invention, the formulation may at least partially impregnate the
non-woven base veil. The formulation may further substantially
uniformly cover the non-woven base veil. In some embodiments of the
present invention, the fibrous non-woven facing material is in the
form of a roll.
[0030] It is yet another object of the present invention to provide
a process for preparing a fibrous non-woven facing material. The
fibrous non-woven facing material may be as defined herein. The
process comprises (a) providing a non-woven base veil comprising a
plurality of randomly oriented fibres, (b) applying the formulation
as defined herein to the non-woven base veil, and (c) heating to
form the fibrous non-woven facing material.
[0031] In various embodiments of the present invention, step (b)
may comprise impregnating the base veil with the formulation. The
process may further comprise step (d) of forming a roll of the
fibrous non-woven facing material. In various embodiments of the
present invention, the fibrous non-woven facing material is a
non-woven wall-covering or ceiling facer.
[0032] It is another object of the present invention to provide a
fibrous non-woven facing material obtained by the process described
herein.
[0033] These objects and embodiments are set out in the appended
independent and dependent claims. It will be appreciated that
features of the dependent claims may be combined with each other
and with features of the independent claims in combinations other
than those explicitly set out in the claims. Furthermore, the
approaches described herein are not restricted to specific
embodiments such as those set out below, but include and
contemplate any combinations of features presented herein.
[0034] The foregoing and other objects, features, and advantages of
the invention will appear more fully hereinafter from a
consideration of the detailed description that follows along with
the accompanying drawings. It is to be expressly understood,
however, that the drawings are for illustrative purposes and are
not to be construed as defining the limits of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a flow-chart which schematically shows the stages
of the method to measure glue penetration.
[0036] FIGS. 2A to 2D are SEM images of calcium carbonate extenders
in accordance with the invention: CaCO.sub.3-1 (FIG. 2A),
CaCO.sub.3-2 (FIG. 2B), CaCO.sub.3-3 (FIG. 2C) and CaCO.sub.3-4
(FIG. 2D). FIGS. 2A to 2D clearly show the non-spherical morphology
of these extenders.
[0037] FIG. 3A is a bar chart comparing the opacity values obtained
in Example 1 for the reference formulation, with each of the
"TiO.sub.2-free" formulations that include CaCO.sub.3-1,
CaCO.sub.3-2, CaCO.sub.3-3 or CaCO.sub.3-4.
[0038] FIG. 3B is a bar chart comparing the whiteness values
obtained in Example 1 for the reference formulation, with each of
the "TiO.sub.2-free" formulations that include CaCO.sub.3-1,
CaCO.sub.3-2, CaCO.sub.3-3 or CaCO.sub.3-4.
[0039] FIG. 3C is a bar chart comparing the glue penetration values
obtained in Example 1 for the reference formulation, with each of
the "TiO.sub.2-free" formulations including CaCO.sub.3-1,
CaCO.sub.3-2, CaCO.sub.3-3 or CaCO.sub.3-4.
[0040] FIG. 4 is an SEM image of a Huntite extender in accordance
with the present invention showing its non-spherical
morphology.
[0041] FIGS. 5A to 5C are bar charts respectively comparing the
opacity, whiteness, and glue penetration values obtained in Example
2 for the reference formulation and each of the "TiO.sub.2-free"
formulations which include a plate-like extender. The plate-like
extenders were the Huntite extender shown in FIG. 4, calcined
kaolin-1, CaCO.sub.3-5 and calcined kaolin-2.
[0042] FIGS. 6A to 6C are bar charts respectively comparing the
opacity, whiteness, and glue penetration values obtained in Example
3 for the reference formulation including a coarse calcium
carbonate filler and the formulation including a finer calcium
carbonate filler instead of the coarse filler. FIGS. 7A to 7C are
bar charts comparing the opacity, whiteness, and glue penetration
values obtained in Example 4 for the reference formulation, the
"TiO.sub.2-free" formulations including CaCO.sub.3-4, calcined
kaolin-1, CaCO.sub.3-3, the Huntite extender shown in FIG. 4,
CaCO.sub.3-5 or calcined kaolin-2 (left), and the "TiO.sub.2-free"
formulations further including the finer calcium carbonate filler
instead of the coarse filler (right).
DETAILED DESCRIPTION
[0043] While various exemplary embodiments are described or
suggested herein, other exemplary embodiments utilizing a variety
of methods and materials similar or equivalent to those described
or suggested herein are encompassed by the general inventive
concepts. Those aspects and features of embodiments which are
implemented conventionally may not be discussed or described in
detail in the interests of brevity. It will thus be appreciated
that aspects and features of apparatus and methods described herein
which are not described in detail may be implemented in accordance
with any conventional techniques for implementing such aspects and
features.
[0044] The general inventive concept relates to a formulation for a
fibrous non-woven facing material which includes a defined extender
to at least partially replace titanium dioxide as the white
pigment. Surprisingly the defined extender, together with the
specific filler, provides a formulation which has comparable
opacity and whiteness as commercial materials containing titanium
dioxide. The extender of the inventive formulation has an irregular
morphology in that it comprises non-spherical particles, and has an
median particle size, d.sub.50, which is equal to or less than 3.5
microns. The formulation also comprises less than 13 wt % titanium
dioxide on a dry solids basis. The filler of the inventive
formulation has an median particle size, d.sub.50, which is equal
to or less than 3.0 microns, a d.sub.90 value of equal to or less
than 6.0 microns and a d.sub.10 value of equal to or less than 1.0
micron.
[0045] In various embodiments of the present invention, the filler
has an median particle size, d.sub.50, which is equal to or less
than 1.5 microns, a d.sub.90 value of equal to or less than 5.0
microns and a d.sub.10 value of equal to or less than 0.5 micron.
In alternative embodiments, the filler has an median particle size,
d.sub.50, which is equal to or less than 2.5 microns, a d.sub.90
value of equal to or less than 6.0 microns and a d.sub.10 value of
equal to or less than 0.9 micron.
[0046] The formulation containing the defined extender and filler,
together with a binder, provides acceptable opacity and whiteness
levels when applied to a non-woven fibrous base veil even without a
significant level of titanium dioxide. The formulation also
improves glue penetration of the base veil, meaning that it is
particularly suited for use in a non-woven wall-covering or ceiling
facer. In particular, the improved glue penetration enhances
downstream application and use of the non-woven facing material.
Accordingly the general inventive concept includes a fibrous
non-woven facing material comprising a non-woven base veil of
randomly oriented fibres together with the formulation, along with
a process of preparing the fibrous non-woven facing material.
[0047] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention belongs.
[0048] By the term "glue penetration" is meant the leakage of glue
from back to front side of the fibrous non-woven facing material,
e.g. wall-covering or ceiling facer, while it is being applied to
the wall. In the present invention, glue penetration is measured
according to the following method; this method is also shown in
FIG. 1:
[0049] (1) take a non-porous wooden panel and mark the region, e.g.
with tape, where glue needs to be applied;
[0050] (2) apply a pre-determined amount of glue uniformly in the
marked area; a dye may be added to assist the process;
[0051] (3) place a non-woven facing material, e.g. wall-covering,
on top of the glue;
[0052] (4) place an absorbing paper of pre-determined weight and
dimensions on top of the non-woven facing material, the absorbing
paper may be tissue paper;
[0053] (5) place a pre-determined weight on top of the tissue
paper; the weight should be uniformly distributed throughout its
dimension; for example, three A4 paper bundles weighing
approximately 8 kg; wait for three minutes to allow any glue to
penetrate from the back to the front of the non-woven facing
material;
[0054] (6) remove the weight; and
[0055] (7) remove and weigh the absorbing paper.
[0056] The glue penetration is then measured according to formula
(1):
Glue .times. .times. penetration .times. .times. ( % ) = weight
.times. .times. of .times. .times. absorbing .times. .times. paper
.times. .times. ( after - before ) glue .times. .times. penetration
total .times. .times. glue .times. .times. applied .times. 100 ( 1
) ##EQU00001##
[0057] This measurement method for glue penetration is used in the
Examples and applicable to the entire description.
[0058] By the term "opacity" is meant "dry opacity", i.e. the level
of how opaque a substance is; it is also referred to as hiding
power, and is measured using a contrast ratio from a
spectrophotometer, e.g. the Color i5 spectrometer available from
X-Rite. The contrast ratio is represented by formula (2):
Contrast .times. .times. ratio = 100 .times. Y B .times. / .times.
Y W ( 2 ) ##EQU00002##
[0059] where Y.sub.B and Y.sub.W are the lightness of the non-woven
product, using the XYZ colour system, over a white and black
background. This measurement method for opacity is used in the
Examples and applicable to the entire description.
[0060] Whiteness is the degree to which a surface is white and is
measured with a spectrophotometer, e.g. the Color i5 spectrometer
as used for opacity. This measurement method for whiteness is used
in the Examples and applicable to the entire description.
[0061] For ease of reference, these and further features of the
present invention are now discussed under appropriate section
headings. However, the teachings under each section are not limited
to the section in which they are found.
[0062] Fibrous Non-Woven Facing Material
[0063] The formulation of the present invention is for a fibrous
non-woven facing material. By the term "facing material" is meant a
material which is applied to a substrate, e.g. a wall, ceiling tile
or the like, in order to change its aesthetic and/or structural
properties. A facing material may, for example, be a layer of
material which is applied to a substrate in order to improve its
appearance and/or its smoothness. Once applied to the substrate,
the facing material layer is intended to "face", i.e. form the
interior, of a structure.
[0064] Put another way, a fibrous non-woven facing material is a
light-weight fibrous composite which is used to improve surface
structure, aesthetics and performance of a substrate for interior
use. In various embodiments of the invention, the fibrous non-woven
facing material is a fibrous non-woven wall covering and thereby
acts as a means of finishing the interior structure of buildings.
Other fibrous non-woven facing materials will be known to the
skilled person, such as a ceiling tile facer, a gypsum board facer
and the like.
[0065] In various embodiments of the invention, the fibrous
non-woven facing material is in the form of a roll. This is
advantageous because it allows the material to be easily stored and
transported.
Binder
[0066] The formulation of the present invention which is suitable
for a fibrous non-woven facing material includes a binder. A binder
is the film-forming or coating-forming element of a composition. It
typically provides adhesion to a substrate, binds pigments and
extenders together, and can determine properties such as
flexibility and durability. The binder included in the formulation
of the present invention can be any binder known in the art. The
binder included in the formulation is not limited.
[0067] In various embodiments of the present invention, the binder
includes both thermosetting and thermoplastic resins. Typically the
binder is a water dispersible emulsion type binder or a solution
type binder. The binder may be selected from the group of materials
consisting of polymers and copolymers of styrene, butadiene,
acrylic and methacrylic monomers, vinyl acetate as well as
polyesters, polyvinyl alcohols, polyurethanes, epoxy compounds,
starch or modified starch, and any mixtures thereof. In preferred
embodiments of the present invention, the binder is selected from
the group of materials consisting of polymers and copolymers of
styrene, butadiene, acrylic and methacrylic monomers, vinyl acetate
as well as polyesters, polyvinyl alcohols and any mixtures thereof.
In particularly preferred embodiments of the present invention, the
binder is selected from the group of materials consisting of
acrylic polymers or copolymers, polyvinyl chloride, styrene
polymers or copolymers, polyvinyl alcohols, polyvinyl acetate,
styrene butadiene rubber, and ethylene vinyl acetate binders, or a
mixture thereof.
[0068] In highly preferred embodiments, the binder is an acrylic
binder, such as polyacrylic acid, or a combination of acrylic and
styrene binders. One example of a suitable binder is an aqueous
dispersion based on copolymers consisting of acrylic esters and
styrene. It will be understood, however, that the present invention
is not limited to these specific binders.
[0069] In some embodiments, the formulation of the invention may be
defined by the amount of binder present, on a dry solids basis. The
binder may, for example, be present in the formulation in an amount
from 5 wt % to 35 wt % on a dry solids basis. Preferably the binder
may be present in an amount from 10 wt % to 35 wt %, more
preferably from 15 wt % to 35 wt %, and particularly preferably
from 18 wt % to 35 wt %, on a dry solids basis.
[0070] In various embodiments of the present invention, the binder
is present in an amount of from 5 wt % to 35 wt % on a dry solids
basis. In other embodiments the binder is present from 5 wt % to 30
wt % on a dry solids basis. Preferably the binder may be present
from 5 wt % to 25 wt % on a dry solids basis.
[0071] In various embodiments of the present invention, the binder
is present in an amount of from 10 wt % to 35 wt % on a dry solids
basis. Preferably the binder may be present from 10 wt % to 30 wt %
on a dry solids basis. More preferably the binder may be present in
an amount of from 10 wt % to 25 wt % on a dry solids basis.
[0072] In various embodiments of the present invention, the binder
is present in an amount of from 15 wt % to 35 wt % on a dry solids
basis. Preferably the binder may be present in an amount of from 15
wt % to 30 wt % on a dry solids basis. More preferably the binder
may be present in an amount of from 15 wt % to 25 wt % on a dry
solids basis.
[0073] The skilled person will appreciate that these wt % values
can be combined with the wt % values disclosed herein for the other
components of the formulation, in particular, the wt % values on a
dry solids basis for the extender and filler. By the term "on a dry
solids basis" is meant the wt % is calculated on the basis of the
dry ingredients before addition of the solvent, e.g. water.
[0074] The formulation may also have a total solids content of from
30% to 85%. In various embodiments of the invention, the total
solids content of the formulation is from 35% to 85%. Preferably
from 40% to 85%, and more preferably from 45% to 85%.
[0075] In other embodiments of the invention, the total solids
content of the formulation is from 30% to 80%. Preferably from 30%
to 75%, and more preferably from 30% to 70%.
[0076] In various exemplary embodiments of the invention, the total
solids content of the formulation is from 40% to 65%.
Extender
[0077] The formulation of the present invention also includes an
extender. As will be appreciated by the skilled person, extenders
are typically solid discrete particles of material that are
insoluble in the binder and incorporated into formulations as
pigments to lower the overall manufacturing cost and improve
certain properties. Extenders may be thought of as a specific or
particular sub-set of fillers and in the context of the present
invention, the extender is used to at least partially replace the
titanium dioxide in the formulation. The extender in the present
formulation may be any extender material known in the art, provided
that it has a non-spherical morphology and an median particle size,
d.sub.50, equal to or less than 3.5 .mu.m, when measured by laser
diffraction spectroscopy as described herein.
[0078] The extender is included in the formulation of the present
invention as an at least partial replacement for titanium dioxide.
In various embodiments of the invention the extender completely
replaces titanium dioxide such that the formulation does not
include a titanium dioxide pigment. In other embodiments the
extender partially replaces the titanium dioxide such that the
formulation contains no more than 13 wt % of titanium dioxide on a
dry solids basis. The titanium dioxide content of the formulation
is discussed in more detail below.
[0079] Suitable extenders for the formulation of the present
invention include inorganic materials such as kaolin or calcined
kaolin, tin oxide, magnesium carbonate, Huntite, calcium-magnesium
carbonate, calcium carbonate, talc, silica, aluminium trihydrate,
titanium-coated calcium carbonate or mixtures thereof, and organic
materials such as lignin, lignin sulfonate, or a protein-based
biomass. Preferably the extender included in the formulation of the
present invention is an inorganic material selected from the above
group.
[0080] In some embodiments of the invention, the extender comprises
kaolin or calcined kaolin, aluminium trihydrate, magnesium
carbonate, Huntite, calcium-magnesium carbonate, calcium carbonate,
or a mixture thereof. In preferred embodiments, the extender
comprises calcium-magnesium carbonate, calcium carbonate, or a
mixture thereof. In more preferred embodiments, the extender
comprises calcium carbonate. The extender may, for example, be a
precipitated calcium carbonate although the invention is not
limited to precipitated calcium carbonate extenders.
[0081] The term "precipitated calcium carbonate" is well-recognised
in the art, and is used interchangeably with "PCC". A PCC is
generally made by hydrating high-calcium quicklime and then
reacting the resulting slurry, termed "milk-of-lime", with carbon
dioxide.
[0082] The median particle size, d.sub.50, of the extender is equal
to or less than 3.5 .mu.m. As noted above, by "median particle
size, d.sub.50", is meant the diameter at which 50% of a sample's
mass is comprised of smaller particles. In other words, 50% of the
particles satisfy the given requirement. It is also known in the
art as the "mass median diameter" or the "average particle diameter
by mass". In the present invention, the median particle size,
d.sub.50, is measured by laser diffraction spectroscopy using a LS
13 320 spectrometer as described herein. In particular, the
material to be measured is prepared as a 10 wt % aqueous slurry and
then analysed with the Standard Optical Model described above on
the LS 13 320 spectrometer.
[0083] In view of the non-spherical morphology of the extender, the
median particle size is calculated on the basis of "equivalent
spherical diameter". According to IUPAC, the equivalent diameter of
a non-spherical particle is equal to a diameter of a spherical
particle that exhibits identical properties to that of the
investigated non-spherical particle. For particles in non-turbulent
motion as in the present invention, the equivalent diameter is
identical to the diameter encountered in Stokes' law.
[0084] In various embodiments of the invention, the median particle
size, d.sub.50, of the extender is equal to or less than 3.5 .mu.m
and greater than 0.6 .mu.m. Preferably the median particle size,
d.sub.50, of the extender is equal to or less than 3.5 .mu.m and
greater than 0.8 .mu.m. More preferably the median particle size,
d.sub.50, of the extender is equal to or less than 3.5 .mu.m and
greater than 1.0 .mu.m.
[0085] In other embodiments of the invention, the median particle
size, d.sub.50, of the extender is equal to or less than 2.0 .mu.m
and greater than 0.6 .mu.m. Preferably the median particle size,
d.sub.50, of the extender is equal to or less than 2.0 .mu.m and
greater than 0.8 .mu.m. More preferably the median particle size,
d.sub.50, of the extender is equal to or less than 2.0 .mu.m and
greater than 1.0 .mu.m.
[0086] As well as the measurement of d.sub.50, the extender may be
characterised by its d.sub.10 and/or d.sub.90 measurements. It is
known in the art that d.sub.10 is the diameter at which 10% of the
sample's mass is comprised of particles with a diameter less than
this value, and d.sub.90 is the diameter at which 90% of the
sample's mass is comprised of particles with a diameter of less
than this value. In the present invention, the measurement of
d.sub.10 and d.sub.90 is by laser diffraction spectroscopy with a
LS 13 320 spectrometer in the same manner as the measurement of
d.sub.50.
[0087] In various embodiments of the invention, the extender has a
d.sub.10 of greater than or equal to 0.1 .mu.m. Preferably the
extender has a d.sub.10 of greater than or equal to 0.1 .mu.m and
less than 0.5 .mu.m. More preferably the extender has a d.sub.10 of
greater than or equal to 0.1 .mu.m and less than 0.4 .mu.m.
[0088] In various embodiments of the invention, the extender has a
d.sub.90 of greater than or equal to 2.0 .mu.m. Preferably the
extender has a d.sub.90 of greater than or equal to 4.0 .mu.m and
less than 20.0 .mu.m. More preferably the extender has a d.sub.90
of greater than or equal to 6.0 .mu.m and less than 20.0 .mu.m.
[0089] In various embodiments of the invention, the extender has a
d.sub.10 of between 0.1 and 0.5 .mu.m, a d.sub.50 of between 0.8
.mu.m and 3.5 .mu.m, and a d.sub.90 of between 2.0 .mu.m and 20.0
.mu.m. Preferably the extender has a d.sub.10 of between 0.1 and
0.4 .mu.m, a d.sub.50 of between 1.0 .mu.m and 3.5 .mu.m, and a
d.sub.90 of between 4.0 .mu.m and 19.0 .mu.m.
[0090] Another parameter which may be used to define the extender
is the refractive index. As noted above, the extender is being used
in the present formulation to at least partially, if not
completely, replace titanium dioxide, and titanium dioxide is known
in its rutile phase, to have a high refractive index of 2.6.
Surprisingly, however, the extender included in the formulation of
the present invention can have a refractive index of less than 2.5,
preferably less than 2.0, more preferably less than 1.9. Without
wishing to be bound by theory, the inventors believe that a lower
refractive index material can be used because of the light
scattering effect of the non-spherical morphology coupled with the
defined particle size distribution.
[0091] In various embodiments of the invention, the formulation
does not therefore include a pigment having a refractive index of
2.5 or more. In preferred embodiments, the formulation does not
include a pigment with a refractive index of 2.4 or more. In more
preferred embodiments, the formulation does not include a pigment
with a refractive index of 2.3 or more.
[0092] In various embodiments of the invention, the extender
comprises kaolin, magnesium carbonate, calcium carbonate, Huntite,
calcium-magnesium carbonate or a mixture thereof and has a
refractive index of less than 2.5, preferably less than 2.0, more
preferably less than 1.9. In some embodiments, the extender is a
precipitated calcium carbonate and has a refractive index of less
than 2.5, preferably less than 2.0, more preferably less than 1.9.
The skilled person will appreciate that the refractive index of
less than 2.5, preferably less than 2.0 and more preferably less
than 1.9, can be combined with the d.sub.50, d.sub.10 and/or
d.sub.90 values set out above for the extender.
[0093] In various embodiments of the invention, the extender has a
d.sub.10 of between 0.1 and 0.5 .mu.m, a d.sub.50 of between 0.8
.mu.m and 3.5 .mu.m, a d.sub.90 of between 2.0 .mu.m and 20.0
.mu.m, and a refractive index of less than 2.5. Preferably the
extender has a d.sub.10 of between 0.1 and 0.4 .mu.m, a d.sub.50 of
between 1.0 .mu.m and 3.5 .mu.m, a d.sub.90 of between 4.0 .mu.m
and 19.0 .mu.m and a refractive index of less than 2.0.
[0094] In other embodiments of the invention, the extender has a
d.sub.10 of between 0.1 and 0.5 .mu.m, a d.sub.50 of between 0.8
.mu.m and 3.5 .mu.m, a d.sub.90 of between 2.0 .mu.m and 20.0
.mu.m, and a refractive index of less than 2.0. Preferably the
extender has a d.sub.10 of between 0.1 and 0.4 .mu.m, a d.sub.50 of
between 1.0 .mu.m and 3.5 .mu.m, a d.sub.90 of between 4.0 .mu.m
and 19.0 .mu.m, and a refractive index of less than 1.9.
[0095] The extender included in the formulation of the present
invention has a non-spherical morphology. By "non-spherical
morphology" is meant that the extender is not made up of spherical
or substantially spherical particles. As is known in the art,
morphology of a material can be characterized by a scanning
electron microscope (SEM). In the present invention, the morphology
of the extender will either be known from commercially available
literature or can be determined by routine SEM measurement.
[0096] In some embodiments the extender has non-spherical
morphology because it comprises plate-shaped particles, rod-shaped
particles, cubic or cuboid-shaped particles, pseudo-cubic shaped
particles, cigar-shaped particles or a combination thereof. Other
non-spherical morphologies are also contemplated by the present
invention and will be known to the skilled person. In preferred
embodiments of the invention, the extender comprises plate-shaped
particles, rod-shaped particles, cigar-shaped particles or a
combination thereof.
[0097] In various embodiments of the invention, the extender has
non-spherical morphology and a refractive index of less than 2.5,
preferably less than 2.0, more preferably less than 1.9. The
non-spherical morphology may include plate-shaped particles,
rod-shaped particles, cubic or cuboid-shaped particles,
pseudo-cubic shaped particles, cigar-shaped particles or a mixture
thereof. In various embodiments of the invention, the extender has
non-spherical morphology as defined herein, a refractive index of
less than 2.5 and comprises kaolin, calcium carbonate, Huntite,
magnesium carbonate, calcium-magnesium carbonate or a mixture
thereof. The extender is preferably a precipitated calcium
carbonate with the recited refractive index and non-spherical
morphology.
[0098] In various embodiments of the invention, the formulation may
be characterized by the amount of extender present, on a dry solids
basis. The amounts of extender may be combined with the above
recited amounts of binder and/or with the below recited amounts of
filler. In various embodiments, the amounts for the binder may be
combined with the sum of the amounts of filler and extender.
[0099] In various embodiments, the formulation of the invention
includes the extender in an amount of from 5 wt % to 90 wt %,
preferably from 10 wt % to 90 wt %, more preferably from 15 wt % to
90 wt %, all on a dry solids basis. In other embodiments the
formulation includes the extender in an amount of from 10 wt % to
90 wt %, preferably from 10 to 85 wt %, more preferably from 10 wt
% to 80 wt %, all on a dry solids basis. In some embodiments, the
formulation includes the extender in an amount of from 15 wt % to
90 wt %, preferably from 15 wt % to 85 wt %, more preferably from
15 wt % to 80 wt %, all on a dry solids basis.
[0100] In various embodiments, the formulation of the invention
includes the extender in an amount of from 5 wt % to 90 wt % and
the binder in an amount of from 5 wt % to 35 wt %, both on a dry
solids basis. Preferably the formulation of the invention includes
the extender in an amount of from 10 wt % to 90 wt % and the binder
in an amount of from 10 wt % to 35 wt %, both on a dry solids
basis. More preferably, the formulation of the invention includes
the extender in an amount of from 15 wt % to 90 wt % and the binder
in an amount of from 10 wt % to 35 wt %, both on a dry solids
basis
[0101] In various embodiments, the formulation of the invention
includes the extender in an amount of from 10 wt % to 85 wt % and
the binder in an amount of from 10 wt % to 35 wt %. Preferably the
formulation includes the extender in an amount of from 15 wt % to
85 wt % and the binder in an amount of from 10 wt % to 30 wt %,
both on a dry solids basis.
[0102] In various exemplary embodiments of the present invention,
the binder is present in an amount of 15 wt % to 25 wt % on a dry
solids basis and the extender is present in an amount of from 10 wt
% to 45 wt %, on a dry solids basis.
[0103] The formulation may also be characterized by a weight ratio
based on dry solids of the binder to the extender. In various
embodiments this weight ratio may be from 0.05:1 to 7:1, 0.1:1 to
7:1, 0.5:1 to 7:1 or 1:1 to 7:1. In other embodiments this weight
ratio may be from 0.05:1 to 6:1, 0.05:1 to 5:1, 0.1:1 to 4:1, 0.5:1
to 3:1 or 1:1 to 2:1. Preferably the binder:extender weight ratio,
based on dry solids, is 1:1 or less, e.g. 0.05:1 to 1:1.
Filler
[0104] The formulation of the present invention includes a filler.
The filler is any inorganic filler known in the art that is
dispersible in water, and has an median particle size, d.sub.50,
equal to or less than 3.0 .mu.m, a d.sub.90 value of equal to or
less than 6.0 .mu.m and a d.sub.10 value of equal to or less than
1.0 .mu.m. In the present invention, the filler is incorporated to
obtain the desired weight and low manufacturing cost.
[0105] The filler may be selected from the group of materials
consisting of kaolin, calcium carbonate, aluminium trihydrate,
magnesium hydroxide, silicon oxide, clay, talc and mixtures
thereof. Preferably the filler is selected from the group of
materials consisting of calcium carbonate, aluminium trihydrate,
clay, talc and mixtures thereof. More preferably the filler is
selected from the group consisting of calcium carbonate, aluminium
trihydrate and mixtures thereof. Most preferred is where the filler
is a calcium carbonate material, for example, a ground calcium
carbonate, or an aluminium trihydrate. The invention is not,
however, limited to ground calcium carbonate fillers or aluminium
trihydrate fillers.
[0106] The term "ground calcium carbonate" is well-recognised in
the art, and is used interchangeably with "GCC". GCC differs from
PCC in that it is formed directly from grinding limestone rock into
a powder, while PCC is prepared via the above process.
[0107] When the filler is aluminium trihydrate, it may be prepared
by any method known in the art. For example, the aluminium
trihydrate may be precipitated, autoclaved or ground aluminium
trihydrate, the invention is not limited in this respect. Such
materials are commercially available.
[0108] The median particle size, d.sub.50, of the filler is equal
to or less than 3.0 .mu.m. The filler is also defined by having a
d.sub.90 value of equal to or less than 6.0 .mu.m and a d.sub.10
value of equal to or less than 1.0 .mu.m. As for the extender,
these particle sizes are measured by laser diffraction spectroscopy
using a LS 13 320 spectrometer as described herein. In particular,
the material to be measured is prepared as a 10 wt % aqueous slurry
and then analysed with the Standard Optical Model described above
on the LS 13 320 spectrometer.
[0109] In various embodiments of the invention, the median particle
size, d.sub.50, of the filler is equal to or less than 3.0 .mu.m
and greater than 0.2 .mu.m, the d.sub.90 is equal to or less than
6.0 .mu.m and equal to or greater than 0.5 .mu.m, and the d.sub.10
is equal to or less than 1.0 .mu.m and equal to or greater than 0.1
.mu.m. Preferably the median particle size, d.sub.50, of the filler
is equal to or less than 3.0 .mu.m and equal to or greater than 0.4
.mu.m, the d.sub.90 is equal to or less than 6.0 .mu.m and equal to
or greater than 1.0 .mu.m, and the d.sub.10 is equal to or less
than 1.0 .mu.m and equal to or greater than 0.1 .mu.m.
[0110] In various embodiments of the invention, the median particle
size, d.sub.50, of the filler is equal to or less than 1.5 .mu.m,
the d.sub.90 is equal to or less than 5.0 .mu.m, and the d.sub.10
is equal to or less than 0.5 .mu.m. Preferably, the median particle
size, d.sub.50, of the filler is equal to or less than 1.0 .mu.m,
the d.sub.90 is equal to or less than 3.0 .mu.m, and the d.sub.10
is equal to or less than 0.3 .mu.m. Particularly preferred is where
the median particle size, d.sub.50, of the filler is equal to or
less than 0.8 .mu.m, the d.sub.90 is equal to or less than 2.0
.mu.m, and the d.sub.10 is equal to or less than 0.2 .mu.m.
[0111] In various embodiments of the invention, the median particle
size, d.sub.50, of the filler is equal to or less than 1.5 .mu.m
and equal to or greater than 0.2 .mu.m, the d.sub.90 is equal to or
less than 5.0 .mu.m and equal to or greater than 0.5 .mu.m, and the
d.sub.10 is equal to or less than 0.5 .mu.m and equal to or greater
than 0.1 .mu.m. Preferably, the median particle size, d.sub.50, of
the filler is equal to or less than 1.0 .mu.m and equal to or
greater than 0.4 .mu.m, the d.sub.90 is equal to or less than 3.0
.mu.m and equal to or greater than 1.0 .mu.m, and the d.sub.10 is
equal to or less than 0.3 .mu.m and equal to or greater than 0.1
.mu.m. Particularly preferred is where the median particle size,
d.sub.50, of the filler is equal to or less than 0.8 .mu.m and
equal to or greater than 0.4 .mu.m, the d.sub.90 is equal to or
less than 2.0 .mu.m and equal to or greater than 1.0 .mu.m, and the
d.sub.10 is equal to or less than 0.2 .mu.m and equal to or greater
than 0.1 .mu.m.
[0112] In alternative embodiments of the invention, the median
particle size, d.sub.50, of the filler is equal to or less than 3.0
.mu.m and equal to or greater than 0.5 .mu.m, the d.sub.90 is equal
to or less than 6.0 .mu.m and equal to or greater than 1.5 .mu.m,
and the d.sub.10 is equal to or less than 1.0 .mu.m and equal to or
greater than 0.2 .mu.m. Preferably the median particle size,
d.sub.50, of the filler is equal to or less than 3.0 .mu.m and
equal to or greater than 1.0 .mu.m, the d.sub.90 is equal to or
less than 6.0 .mu.m and equal to or greater than 2.5 .mu.m, and the
d.sub.10 is equal to or less than 1.0 .mu.m and equal to or greater
than 0.3 .mu.m.
[0113] In various embodiments of the invention, the median particle
size, d.sub.50, of the filler is equal to or less than 2.8 .mu.m,
the d.sub.90 is equal to or less than 6.0 .mu.m, and the d.sub.10
is equal to or less than 1.0 .mu.m. Preferably, the median particle
size, d.sub.50, of the filler is equal to or less than 2.5 .mu.m,
the d.sub.90 is equal to or less than 6.0 .mu.m, and the d.sub.10
is equal to or less than 0.9 .mu.m.
[0114] In various embodiments of the invention, the median particle
size, d.sub.50, of the filler is equal to or less than 2.8 .mu.m
and equal to or greater than 0.5 .mu.m, the d.sub.90 is equal to or
less than 6.0 .mu.m and equal to or greater than 1.5 .mu.m, and the
d.sub.10 is equal to or less than 1.0 .mu.m and equal to or greater
than 0.2 .mu.m. Preferably, the median particle size, d.sub.50, of
the filler is equal to or less than 2.5 .mu.m and equal to or
greater than 1.0 .mu.m, the d.sub.90 is equal to or less than 6.0
.mu.m and equal to or greater than 3.0 .mu.m, and the d.sub.10 is
equal to or less than 0.9 .mu.m and equal to or greater than 0.2
.mu.m.
[0115] Another parameter which may be used to define the filler is
the refractive index. The filler is being used in the present
formulation to further improve the properties of the formulation on
replacement of the titanium dioxide, and surprisingly, the
inventors found that the filler included in the formulation of the
present invention can have a refractive index of less than 2.5,
preferably less than 2.0. These refractive index values are lower
than that for titanium dioxide (in rutile phase). In a similar
manner to the extender, the inventors believe that a lower
refractive index material can be used because of the light
scattering effect of the extender and the light scattering effect
of the filler's particle size distribution.
[0116] As noted above, this means that in various embodiments, the
invention does not include a pigment having a refractive index of
2.5 or more in the formulation. In preferred embodiments, the
formulation does not include a pigment with a refractive index of
2.4 or more. In more preferred embodiments, the formulation does
not include a pigment with a refractive index of 2.3 or more.
[0117] In various embodiments of the invention, the filler has a
refractive index of less than 2.5 and comprises calcium carbonate,
aluminium trihydrate or a mixture thereof; preferably the
refractive index is less than 2.0, more preferably less than 1.9.
In some embodiments, the filler is a ground calcium carbonate and
has a refractive index of less than 2.5, preferably less than 2.0,
and more preferably less than 1.9. The skilled person will
appreciate that the refractive index of the filler can be combined
with the d.sub.50, d.sub.10 and d.sub.90 values set out above for
the filler. Additionally, these features can be combined with the
definitions of the binder and/or extender described herein.
[0118] In various embodiments of the invention, the filler has a
d.sub.10 of between 0.1 and 1.0 .mu.m, a d.sub.50 of between 0.2
.mu.m and 3.0 .mu.m, a d.sub.90 of between 0.5 .mu.m and 6.0 .mu.m,
and a refractive index of less than 2.5. Preferably the filler has
a d.sub.10 of between 0.1 and 1.0 .mu.m, a d.sub.50 of between 0.4
.mu.m and 3.0 .mu.m, a d.sub.90 of between 1.0 .mu.m and 6.0 .mu.m,
and a refractive index of less than 2.0.
[0119] In various embodiments of the invention, the filler has a
d.sub.10 of between 0.1 and 1.0 .mu.m, a d.sub.50 of between 0.2
.mu.m and 3.0 .mu.m, a d.sub.90 of between 0.5 .mu.m and 6.0 .mu.m,
and a refractive index of less than 1.9. In various embodiments of
the invention, the filler has a d.sub.10 of between 0.1 and 1.0
.mu.m, a d.sub.50 of between 0.4 .mu.m and 3.0 .mu.m, a d.sub.90 of
between 1.0 .mu.m and 6.0 .mu.m, and a refractive index of less
than 1.9.
[0120] In various embodiments of the invention, the filler has a
d.sub.10 of between 0.1 and 0.5 .mu.m, a d.sub.50 of between 0.2
.mu.m and 1.5 .mu.m, a d.sub.90 of between 0.5 .mu.m and 5.0 .mu.m,
and a refractive index of less than 2.5 or less than 2.0.
Preferably the filler has a d.sub.10 of between 0.1 and 0.3 .mu.m,
a d.sub.50 of between 0.4 .mu.m and 1.0 .mu.m, a d.sub.90 of
between 1.0 .mu.m and 3.0 .mu.m, and a refractive index of less
than 2.0 or less than 1.9.
[0121] In alternative embodiments of the invention, the filler has
a d.sub.10 of between 0.2 and 1.0 .mu.m, a d.sub.50 of between 0.5
.mu.m and 2.0 .mu.m, a d.sub.90 of between 1.5 .mu.m and 6.0 .mu.m,
and a refractive index of less than 2.5 or less than 2.0.
Preferably the filler has a d.sub.10 of between 0.2 and 1.0 .mu.m,
a d.sub.50 of between 1.0 .mu.m and 2.0 .mu.m, a d.sub.90 of
between 2.5 .mu.m and 6.0 .mu.m, and a refractive index of less
than 2.0 or less than 1.9.
[0122] In various embodiments of the invention, the filler has a
d.sub.10 of between 0.2 and 1.0 .mu.m, a d.sub.50 of between 0.5
.mu.m and 2.8 .mu.m, a d.sub.90 of between 1.5 .mu.m and 6.0 .mu.m,
and a refractive index of less than 2.5 or less than about 2.0.
Preferably the filler has a d.sub.10 of between 0.2 and 0.6 .mu.m,
a d.sub.50 of between 1.0 .mu.m and 2.0 .mu.m, a d.sub.90 of
between 3.0 .mu.m and 6.0 .mu.m, and a refractive index of less
than 2.0 or less than 1.9.
[0123] The morphology of the filler is not limited. The filler may
have spherical or non-spherical morphology.
[0124] In various embodiments of the invention, the formulation may
be characterized by the amount of filler present, on a dry solids
basis. The amount of filler can be combined with the above recited
amounts of binder and/or extender. In various embodiments, the sum
of filler and extender is characterized.
[0125] In various embodiments of the invention, the formulation
includes the filler in an amount of from 5 wt % to 90 wt %,
preferably from 10 wt % to 90 wt %, more preferably from 15 wt % to
90 wt %, all on a dry solids basis. In other embodiments the
formulation includes the filler in an amount of from 10 wt % to 90
wt %, preferably from 10 to 85 wt %, more preferably from 10 wt %
to 80 wt %, all on a dry solids basis. In some embodiments, the
formulation includes the filler in an amount of from 15 wt % to 90
wt %, preferably from 15 wt % to 85 wt %, more preferably from 15
wt % to 80 wt %, all on a dry solids basis.
[0126] In various embodiments of the invention, the formulation
includes the binder in an amount of from 5 wt % to 35 wt %, the
extender in an amount of from 5 wt % to 90 wt % and the filler in
an amount of from 5 wt % to 90 wt %, all on a dry solids basis.
Preferably, the formulation includes the binder in an amount of
from 5 wt % to 30 wt %, the extender in an amount of from 5 wt % to
85 wt % and the filler in an amount of from 10 wt % to 90 wt %, all
on a dry solids basis. More preferably, the formulation includes
the binder in an amount of from 5 wt % to 25 wt %, the extender in
an amount of from 5 wt % to 80 wt % and the filler in an amount of
from 15 wt % to 90 wt %, all on a dry solids basis.
[0127] In various embodiments, the formulation of the invention can
be characterized by a weight ratio based on dry solids of the
extender to the filler. This weight ratio may be from 0.05:1 to
18:1. Preferably the weight ratio based on dry solids of the
extender to the filler may be 0.05:1 to 10:1. More preferably from
0.05:1 to 5:1, and even more preferably from 0.05:1 to 2:1.
[0128] In other embodiments the weight ratio based on dry solids of
the extender to the filler may be from 0.1:1 to 18:1. Preferably
from 0.5:1 to 18:1, more preferably from 1:1 to 18:1, and even more
preferably from 1:2 to 18:1.
[0129] In various embodiments, the formulation of the invention
includes more filler than extender. In this instance, the weight
ratio on a dry solids basis of extender:filler may be from 1:1.1 to
1:10. Preferably from 1:1.5 to 1:5 and more preferably from 1:1.5
to 1:4.
[0130] The formulation may also be defined by a weight ratio based
on dry solids of the binder to the sum of the extender and the
filler. In various embodiments of the invention, this weight ratio
is from 0.05:1 to 7:2. In preferred embodiments, the weight ratio
of binder:extender+filler is from 0.05:1 to 5:2. In more preferred
embodiments, this weight ratio is from 0.05:1 to 2:1, even from
0.05:1 to 1:1.
[0131] It will be understood by the skilled person that the weight
ratios defined herein for the binder, extender and/or filler may be
combined.
[0132] Titanium Dioxide
[0133] The general inventive concept of the present formulation is
that it can contain less than 13 wt % titanium dioxide on a dry
solids basis and yet maintains or improves the opacity and
whiteness of commercially available formulations. This result can
be seen in the Examples. In various embodiments of the invention,
the formulation comprises less than 12 wt % on a dry solids basis
of titanium dioxide, preferably less than 10 wt % of titanium
dioxide, on a dry solids basis, more preferably less than 5 wt %,
and even more preferably less than 1 wt %.
[0134] In exemplary embodiments of the invention, there is
substantially no titanium dioxide in the formulation. The
formulation is described herein as being substantially free or free
of titanium dioxide; the expression "substantially free" having the
definition set out above.
Additional Components
[0135] The formulation of the present invention is an aqueous
formulation and so will include water in an amount sufficient to
provide the desired rheological properties, e.g. viscosity, to the
composition. These properties may be determined by the chosen form
of application for the facing material and/or for retention of the
composition on the surfaces of the fibres of the base veil. The
water content of the formulation may be determined by the dry
content of the formulation, as known in the art. For example, if
the dry content is from 30 to 85%, the water content will be 70 to
15%. Other water content values are also possible and will be
readily determined by the skilled person.
[0136] The formulation of the present invention may also include
other, optional additives and components. Such optional additives
may include colorants (e.g. pigments), dispersants, antifoam
agents, emulsifiers, optical brighteners, viscosity modifiers,
surfactants, etc. Suitable additives within these categories are
known in the art and the skilled person would be able to routinely
determine their suitability for a fibrous non-woven facing
material.
[0137] Suitable dispersants include polyacrylates, which may be
sodium, ammonium and/or potassium neutralized and/or
hydrophobically modified. Suitable antifoam agents or defoamers may
be mineral oil based, silicone based etc. They may include
emulsions and/or dispersions of mineral, paraffin, or vegetable
oils, dispersions of polydimethylsiloxane (PDMS) fluids and silica
which has been hydrophobized with polydimethylsiloxane or other
materials, and particles made of amide waxes such as
ethylenebis-stearamide or hydrophobized silica.
[0138] Suitable viscosity modifiers include associative and
non-associative acrylics, polyurethanes, glycerol,
1.2.4-butanetriol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol
and poly(ethylene glycol). Suitable surfactants include any ionic
or non-ionic surfactants. Ionic surfactants may include sulfates,
sulfonates, phosphates and carboxylates such as alkyl sulfates,
ammonium lauryl sulfates, sodium lauryl sulfates, alkyl ether
sulfates, sodium laureth sulfate and sodium myreth sulfate, dioctyl
sodium sulfosuccinate, perfluorooctanesulfonate,
perfluorobutanesulfonate, alkyl benzene sulfonates, alkyl aryl
ether phosphates, alkyl ether phosphates, and alkyl carboxylates.
Non-ionic surfactants may include polyethers, polyoxyalkylene
derivatives of hexitol, partial long-chain fatty acid esters,
ethylene oxide derivatives of long-chain alcohols, ethoxylated
vegetable oil, and ethylene oxide/propylene oxide copolymers.
[0139] The level of optional additives is not significant in the
present invention. In various embodiments the optional additives
may be present up to 3 wt % on a dry solids basis. In preferred
embodiments the optional additives may be present up to 2 wt % on a
dry solids basis. In more preferred embodiments the optional
additives may be present up to 1.5 wt % on a dry solids basis. The
expression "up to" is intended to include zero as these additives
are optional in the formulation. In various embodiments, however,
the additives may be present in an amount of from 0.01 wt % to 3 wt
% on a dry solids basis. In preferred embodiments the additives may
be present in an amount of from 0.01 wt % to 2 wt % on a dry solids
basis. In more preferred embodiments the additives may be present
in an amount of from 0.01 wt % to 1.5 wt % on a dry solids
basis.
[0140] With respect to the total weight of the formulation, i.e.
the formulation containing the dry solids and solvent (e.g. water),
the additives may be present up to 10 wt %. Preferably the
additives may be present up to 7.5 wt %, more preferably up to 5 wt
% of the total weight of the formulation. In various embodiments,
the additives may be present in an amount of from 0.1 wt % to 10 wt
% of the total weight of the formulation. In preferred embodiments
the additives may be present in an amount of from 0.1 wt % to 7.5
wt % of the total weight of the formulation. In more preferred
embodiments, the additives may be present in an amount of from 0.1
wt % to 5 wt % of the total weight of the formulation.
Non-Woven Base Veil
[0141] The present invention also provides a fibrous non-woven
facing material comprising a non-woven base veil and the
formulation. As is known in the art, the term "veil" refers to a
web of intermingled, randomly oriented fibres made according to a
wet-laid process. This term may be used interchangeably herein with
"sheet" or "mat".
[0142] The non-woven base veil comprises a plurality of randomly
oriented fibres. These fibres may comprise one or more glass
fibres, carbon fibres, mineral fibres, natural fibres, synthetic
fibres, or a blend thereof. In some embodiments, the fibres
comprise one or more glass fibres, synthetic fibres, or a blend
thereof. The glass fibres can be made from any type of glass.
Examples of glass fibres include A-type glass fibres, C-type glass
fibres, E-type glass fibres, S-type glass fibres, ECR-type glass
fibres, Hiper-tex.RTM., wool glass fibres, and combinations
thereof.
[0143] The term "natural fibre" refers to plant fibres extracted
from any type of plant, including, but not limited to, the stem,
seeds, leaves, roots, or phloem. Examples of natural fibres which
may be suitable for use in the present invention include basalt,
cotton, jute, bamboo, ramie, bagasse, hemp, coir, linen, kenaf,
sisal, flax, henequen, and combinations thereof. The term
"synthetic fibres" refers to any man-made fibre having suitable
reinforcing characteristics, such as polyester, polyethylene,
polyethylene terephthalate, polypropylene, polyamide, aramid, and
polyaramid fibres, and combinations thereof. The term "mineral
fibres" refers to any non-metallic, inorganic fibres, such as
mineral wool fibres: fibres formed by spinning or drawing molten
mineral or rock minerals such as slag and ceramics. These include
alkaline earth silicate wool, alumina silicate wool,
polycrystalline wool, kaowool, and combinations thereof.
[0144] In preferred embodiments, the non-woven base veil comprises
a plurality of randomly oriented fibres which are a blend of glass
fibres and synthetic fibres, such as a blend of glass fibres and
polymer fibres. The polymer fibres include those made from
polypropylene, polyesters, or a combination thereof. In some
embodiments, the polymer fibres are formed from a polyester such as
polyethylene terephthalate.
[0145] In some embodiments, the non-woven base veil comprises a
plurality of randomly oriented fibres which are a blend of 10 to
100 percent by weight glass fibres, and 0 to 90 percent by weight
polymer fibres as described above. In other embodiments, the fibres
include a blend of 50 to 90 percent by weight glass fibres and 10
to 50 percent by weight polymer fibres as described above, or from
75 to 90 percent by weight glass fibres and 10 to 25 percent by
weight polymer fibres as described above.
[0146] The non-woven base veil may be formed by conventional
wet-laid processes known to those skilled in the art. Such methods
can be viewed as modified papermaking processes, and generally
involve forming an aqueous slurry of short-length fibres (referred
to in the art as "white water") under agitation in a mixing tank,
then feeding the slurry onto a moving screen on which the fibres
enmesh themselves into a freshly prepared wet-laid fibre base veil,
while excess water is separated from the fibres. A suitable process
is described in U.S. Pat. No. 6,497,787 B1.
[0147] Machinery such as wire cylinders, Fourdrinier machines,
Stevens Former, Roto Former, Inver Former and Venti Former machines
can be used to form the wet-laid base veil. In such equipment, a
head box deposits the slurry onto a moving wire screen. Suction or
vacuum then removes the water resulting in the wet-laid veil.
[0148] Removal of water is typically followed by the application of
an adhesive binder composition to the base veil. The adhesive
binder composition can be any suitable binder composition known in
the art and includes a binder as defined hereinabove. The binder
composition may, for example, include a binder selected from
acrylic, polyvinyl chloride, styrene, PVOH, polyvinyl acetate,
styrene butadiene rubber, and ethylene vinyl acetate binders. In
some embodiments, the binder composition comprises a polyvinyl
alcohol binder.
[0149] The composition is typically an aqueous-based fluid and is
impregnated directly into the fibrous veil and set or cured
thereafter to provide the desired base veil integrity. The adhesive
binder can be applied to the wet-laid base veil using any suitable
equipment, such as a curtain coater or a dip and squeeze
applicator. Drying or curing may then be carried out in an oven and
once in the oven, the wet-laid base veil may be heated to a
temperature of up to 150-220.degree. C., for a period of time not
usually exceeding 1 or 2 minutes. The skilled person will be aware
of the amount of adhesive binder required to form a suitable
non-woven base veil, and can readily determine this by routine
procedure. The skilled person will also know or be able to
routinely determine the drying conditions required.
[0150] Following formation of the non-woven base veil, the
formulation of the invention is applied thereto. In various
embodiments, the non-woven base veil has at least a first surface
and a second surface, and the formulation at least partially coats
the first surface. In order to form a fibrous non-woven facing
material as defined herein, the skilled person will understand that
the first surface is the surface which is intended to face the
interior of the structure, e.g. the inner surface of a wall in a
building or the like. In preferred embodiments of the invention,
the formulation completely coats the first surface of the base
veil. For example, the formulation may substantially uniformly coat
the first surface of the non-woven base veil. By the expression
"substantially uniformly coat" means that to the naked eye, the
first surface of the base veil has no visible imperfections.
[0151] In other embodiments of the invention, the formulation at
least partially impregnates the non-woven base veil. Preferably the
formulation fully impregnates the non-woven base veil. By the terms
"impregnate", "impregnating" or "impregnated" is meant integrating
the formulation into the base veil. The method of impregnating may
be conducted by any method suitable for integrating or
incorporating the formulation into the fibrous veil. For example,
suitable methods include using a size press such as a Foulard
applicator, a binder wire, rotary screen, dipping roll, spraying,
coating equipment and the like.
[0152] The formulation may be impregnated into the veil at any time
after its formation. In particular, the formulation may be
impregnated after formation of the veil in a formation chamber,
such as on a wire, or after being passed through a first dryer.
While other additional agents or coatings may be applied,
preferably only the formulation of the present invention is
contacted with the base veil.
[0153] Following application of the formulation to the non-woven
base veil, whether by coating, impregnating or otherwise, the veil
is dried to form the fibrous non-woven facing material. Accordingly
in another aspect, the present invention provides a process for
preparing a fibrous non-woven facing material as described herein.
Along with the steps of (a) providing a non-woven base veil
comprising a plurality of randomly oriented fibres, (b) applying
the formulation of the present invention to the non-woven base
veil, and (c) heating to form the fibrous non-woven facing
material, the process may further comprise impregnating the base
veil with the formulation as part of step (b). Additionally the
process may further comprise a step (d) of forming a roll of the
fibrous non-woven facing material. As already described above, the
fibrous non-woven facing material is preferably a non-woven wall
covering.
[0154] The heating of the veil with the applied formulation
typically takes place in a second dryer (the first dryer being used
following application of the adhesive binder composition to the
fibres to form the non-woven base veil). The temperature of the
second dryer may be between 150.degree. C. and 220.degree. C. More
specifically, the heating of the veil with the applied formulation
involves curing the formulation so as to form the non-woven facing
material. Suitable temperatures and times to cure and form the
facing material are known in the art or can be routinely determined
by the skilled person.
[0155] In order for the fibrous non-woven facing material to be
most useful, it is preferred that the material be flexible enough
to be rolled up into rolls of continuous sheet.
Properties
[0156] In various embodiments, the fibrous non-woven material
prepared from the formulation of the present invention has improved
properties relative to commercially available formulations for
non-woven facing materials. The present invention also therefore
provides a fibrous non-woven facing material obtained by the
process described herein.
[0157] In various embodiments of the invention, the fibrous
non-woven facing material obtained by the process described herein
has a comparable or improved opacity level. Preferably the fibrous
non-woven facing material has a comparable opacity level. By the
term "comparable" is mean within 3%, preferably within 2%.
Preferably said fibrous non-woven facing material has an opacity
level of at least 80.0. More preferably said fibrous non-woven
facing material has an opacity level of at least 85.0. Most
preferably said fibrous non-woven facing material has an opacity
level of at least 90.0.
[0158] In various embodiments of the invention, the fibrous
non-woven facing material obtained by the process described herein
has a comparable or improved whiteness level. The term "comparable"
has the same meaning as above, preferably the term "comparable"
means within 2%. Preferably said fibrous non-woven facing material
has a whiteness of at least 93.0 and more preferably at least
94.0.
[0159] In various embodiments of the invention, the fibrous
non-woven facing material obtained by the process described herein
has an improved glue penetration level. Preferably said fibrous
non-woven facing material has a glue penetration of less than 8.0%
according to formula (1) and the measurement method described
herein. More preferably said fibrous non-woven facing material has
a glue penetration of less than 7.5%.
[0160] Having generally described this invention, a further
understanding can be obtained by reference to certain specific
examples illustrated below which are provided for purposes of
illustration only and are not intended to be all inclusive or
limiting unless otherwise specified.
EXAMPLES
[0161] In the following examples, the glue penetration, opacity and
whiteness were determined according to the measurement methods
described above.
[0162] The following materials were used as the filler or extender,
and for consistency, the d.sub.10, d.sub.50 and d.sub.90 particle
sizes were determined according to the measurement method described
above; namely a 10 wt % aqueous slurry of the material to be
measured was prepared and the slurry then analysed with the
above-defined Standard Optical Model on the LS 13 320 spectrometer.
The results of these particle size measurements are set out in
Table I.
TABLE-US-00001 TABLE I Particle Size Median D10 D50 D90 Component
Sample (.mu.m) (.mu.m) (.mu.m) (.mu.m) Extender CaCO.sub.3-4 3.25
0.37 3.25 6.99 Extender CaCO.sub.3-2 1.49 0.29 1.49 7.28 Extender
CaCO.sub.3-3 1.54 0.30 1.54 4.97 Extender CaCO.sub.3-1 1.51 0.30
1.51 7.62 Extender Calcined 1.85 0.26 1.85 10.22 kaolin-2 Extender
Calcined 1.19 0.21 1.19 6.01 kaolin-1 Filler Coarse CaCO.sub.3 0.97
0.22 0.97 4.77 Filler Fine CaCO.sub.3 0.48 0.18 0.48 1.38 Extender
Huntite 1.11 0.19 1.11 18.47 Extender CaCO.sub.3-5 1.31 0.31 1.13
2.64
Example 1: Removal of TiO.sub.2 and Inclusion of a Fine Particle
Size, Non-Spherical Extender
[0163] The main role of TiO.sub.2 in current formulations for
non-woven wall coverings is to provide opacity due to its high
refractive index of 2.6. To find a replacement for TiO.sub.2, the
present inventors firstly employed an extender with a fine particle
size. The extender also contained non-spherical particles. Without
wishing to be bound by theory, the inventors believed that the fine
particle size may enhance the scattering of light and provide a
comparable opacity to TiO.sub.2. The morphology of the extender may
also contribute to the opacity level.
[0164] Firstly a commercially available TiO.sub.2-containing
formulation (also referred to herein as the reference formulation)
was modified by removing the titanium dioxide, and including one of
the following non-spherical extenders characterised in Table I
above: CaCO.sub.3-1, CaCO.sub.3-2, CaCO.sub.3-3 or CaCO.sub.3-4.
Each of these extenders is commercially available, and the
non-spherical morphology of these materials can be seen from the
SEM images of FIGS. 2A to 2D; FIGS. 2A to 2D show in particular how
the CaCO.sub.3-1, CaCO.sub.3-2, CaCO.sub.3-3 and CaCO.sub.3-4
extenders each have rod-like morphology. The reference formulation
also included a binder and a filler.
[0165] Once prepared, the formulations were impregnated into a
non-woven base veil and cured in an oven at 200.degree. C. The
non-woven base veil was prepared according to the wet-laid process
described above with suitable glass fibres.
[0166] The fibrous non-woven facing materials containing the above
formulations were then tested for opacity, whiteness, and glue
penetration, according to the measurement methods described above.
The results are shown in FIGS. 3A to 3C.
[0167] Each of the extenders used in Example 1 was a precipitated
calcium carbonate, and in order of median particle size, d.sub.50,
they are:
CaCO.sub.3-1/CaCO.sub.3-2<CaCO.sub.3-3<CaCO.sub.3-4.
CaCO.sub.3-1 and CaCO.sub.3-2 have comparable d.sub.50 measurements
of 1.51 and 1.49 microns respectively (see Table I). It can
therefore be concluded from FIGS. 3A and 3B that opacity and
whiteness are strongly associated with particle size; notably, as
the particle size of the extender decreases, the opacity and
whiteness increase. It can be concluded from FIG. 3C that glue
penetration is also associated with particle size since this
property improved (decreased) with increasing particle size.
[0168] The removal of TiO.sub.2 and inclusion of a reduced particle
size, non-spherical extender thus provides numerous advantages for
a fibrous non-woven facing material. Namely comparable opacity and
whiteness and improved glue penetration.
Example 2: Removal of TiO.sub.2 and Use of a Non-Spherical, Reduced
Particle Size Extender
[0169] As an extension to the results seen in Example 1,
experiments were carried out to determine the effect of plate-like
extender morphology on the opacity, whiteness, and glue penetration
of a fibrous non-woven facing material. In Example 2, the TiO.sub.2
was therefore removed from the commercially available reference
formulation used in Example 1 and one of the following plate-like
extenders was included: calcined kaolin-1, calcined kaolin-2,
Huntite or CaCO.sub.3-5. Each of these extenders is characterised
in Table I above and is commercially available. The plate-like
morphology of the Huntite extender can be seen from the SEM image
of FIG. 4.
[0170] Once prepared, the formulations were applied to the
non-woven base veil and cured in the same manner as Example 1. The
resulting fibrous non-woven facing materials were then tested for
opacity, whiteness, and glue penetration according to the
measurement methods described above. The results are shown in FIGS.
5A to 5C.
[0171] It can be seen from FIGS. 5A to 5C how using plate-like
morphology extenders is also advantageous. Interestingly, all of
the plate-like extenders provided comparable opacity and whiteness.
All of the plate-like extenders also reduced and hence improved
glue penetration.
Example 3: Replacement of Coarse CaCO.sub.3 Filler with Finer
CaCO.sub.3 Filler
[0172] To determine the role of the filler, the coarse CaCO.sub.3
filler included in the reference formulation of Example 1 was
replaced with a finer CaCO.sub.3 filler. Specifically, the coarse
CaCO.sub.3 filler characterised in Table I was replaced with the
fine CaCO.sub.3 filler of Table I. It can be seen from Table I that
the fine CaCO.sub.3 filler had a d.sub.10 value of less than 0.5
.mu.m and a d.sub.50 value of less than 1 .mu.m when measured by
laser diffraction spectroscopy as described above. Further, the
fine CaCO.sub.3 filler had a d.sub.90 value of less than 2
.mu.m.
[0173] Once prepared, the formulations were applied to a non-woven
base veil and cured in the same manner as Example 1. The fibrous
non-woven facing material was then measured for opacity, whiteness,
and glue penetration according to the measurement methods described
above. The results are shown in FIGS. 6A to 6C where the
formulation with the coarse filler is referred to "Ref (1.5
um)".
[0174] It can be seen from FIGS. 6A and 6B how replacing coarser
calcium carbonate filler with finer calcium carbonate filler
significantly improved the opacity and whiteness of the
formulation. This is consistent with the results of Example 1.
Additionally, having a finer filler was shown to improve glue
penetration. In summary, having a filler with a reduced particle
size significantly improves the key properties of the non-woven
facing material.
Example 4: Combination of Finer CaCO.sub.3 Filler and
Non-Spherical, Reduced Particle Size Extender
[0175] It can be learnt from Examples 1 and 2 that including an
extender meeting the requirements of the present invention in a
titanium dioxide-free formulation improves glue penetration while
maintaining opacity and whiteness. It can also be learnt from
Example 3 that using a finer calcium carbonate filler is helpful
for glue penetration, opacity and whiteness. In view of these
results, experiments were therefore conducted which combined the
finer CaCO.sub.3 filler, and the finer and non-spherical extender
in a TiO.sub.2-free formulation.
[0176] The reference formulation used in Example 1 was therefore
modified by removing TiO.sub.2, using the finer calcium carbonate
filler of Table I, and including an extender selected from
CaCO.sub.3-4, calcined kaolin-1, CaCO.sub.3-3, Huntite,
CaCO.sub.3-5 or calcined kaolin-2. The formulations were then
applied to a non-woven base veil and cured in the same manner as
Example 1. The resulting fibrous non-woven facing material was
tested for opacity, whiteness, and glue penetration according to
the measurement methods described herein, and the results are shown
in FIGS. 7A to 7C alongside the results obtained in Example 3.
[0177] FIG. 7A shows how the use of a finer CaCO.sub.3 filler
maintained the comparable opacity levels obtained with the
extenders. FIG. 7B shows a similar trend for whiteness.
Surprisingly, however, the combination of finer CaCO.sub.3 filler
and non-spherical, reduced particle size extender led to a
significant improvement in glue penetration (FIG. 7C).
[0178] In summary, the combination of a finer CaCO.sub.3 filler and
non-spherical, finer extender provided a TiO.sub.2-free formulation
for a fibrous non-woven facing material which exhibited comparable
opacity and whiteness to a titanium-dioxide containing commercial
product whilst improving the glue penetration. These are
significant advantages, which alongside the improvements which
arise from replacing titanium dioxide (e.g. reduced cost volatility
and environmental impact); mean that the present invention is an
important development in the technical field of non-woven facing
materials.
[0179] The various embodiments described herein are presented only
to assist in understanding and teaching the claimed features. These
embodiments are provided as a representative sample of embodiments
only, and are not exhaustive and/or exclusive. It is to be
understood that advantages, embodiments, examples, functions,
features, structures, and/or other aspects described herein are not
to be considered limitations on the scope of the disclosure as
defined by the claims or limitations on equivalents to the claims,
and that other embodiments may be utilised and modifications may be
made without departing from the scope of the claimed disclosure.
Various embodiments of the present disclosure may suitably
comprise, consist of, or consist essentially of, appropriate
combinations of the disclosed elements, components, features,
parts, steps, means etc. other than those specifically described
herein. In addition, this disclosure may include other disclosures
not presently claimed, but which may be claimed in future.
* * * * *
References